IPA: /ʌnˈtʃeɪstli/
KK: /ʌnˈtʃeɪstli/
In a way that is not pure or modest, often referring to sexual behavior.
She spoke unchastely about her past relationships.
Unchastely → It is formed from "un-" (meaning not) and "chaste" (from Latin "castus", meaning pure or morally clean) and the suffix "-ly" (meaning in a manner). The word "unchastely" means in a manner that is not pure or morally clean.
Think of 'not' ('un-') being added to 'pure' ('chaste') to remember that 'unchastely' describes behavior that is not pure or morally clean.